A. Field of Invention
This invention pertains to an apparatus for monitoring railroad trains, and more specifically to an infrared apparatus for detecting hot bearings and hot wheels of a train.
B. Description of the Prior Art
A major source of problems in the field of railroad transportation and especially freight railroad trains have been overheated bearings. An overheated bearing on a single car truck may cause the wheel journal to break, causing the car to overturn and the train to derail. Such derailments are extremely dangerous, and can cause immense economic expense. In order to prevent such derailments, infrared hot bearing detecting apparatuses are presently in service on railroads in virtually every major country in the world. The original system for these detectors was installed in the United States in 1956. Typically, such systems use an infrared scanner disposed on the railroad bed adjacent to the track and oriented at an angle upwardly so that it scans successively the bearing assemblies or housings and the bottom of the railroad car. The readings obtained from the car bottom are used as an indicia of the ambient temperature. Over the years various changes have been made in the design of railroad cars and the detectors must have the ability to scan and accurately measure the temperature of the bearings on a large number of car configurations. Existing detectors have problems accomplishing this task successfully. For example, the latest articulated freight cars do not present a uniform bottom to the scanner which can be used as an accurate ambient temperature reference, particularly when empty or partially loaded. Another problem with existing detectors has been that the bottom of empty hopper type freight cars may get heated up by the sun giving a false indication of the ambient temperature. In addition, radiation from the heated ballast in the summer raises the temperature of the car bottoms.
Another problem for railroads results from overheated wheels due to defective brake mechanisms or unreleased handbrakes. These mechanisms heat the wheels of a car to dangerous levels, causing the wheels to lose their tensile strength. Of course the dangerous temperature limit for a hot wheel is much higher than the dangerous temperature limit for a hot bearing and therefore a temperature for a wheel may be perfectly acceptable but may be too high for a bearing. Until now, this and other various physical constraints dictated the use of separate hot wheel and hot bearing detectors. In fact, many hot bearing detectors included means for occluding any hot wheel readings to insure that a normal wheel reading does not result in a false hot bearing reading. Of course a false hot bearing reading (or for that matter, a false hot wheel reading), while not as dangerous, is also very expensive if it results in the stopping of a train. False train stops in the application of prior art hot bearing detectors are the greatest detriment to the application of hot bearing detectors.
U.S. Pat. No. 2,818,508 to Johanson et al. discloses a hot bearing detector with a scanner oriented transversely to the train movement, and a wheel sensor which disables the scanner to insure that hot wheel readings are excluded.
U.S. Pat. No. 3,545,005 to Gallagher discloses a hot bearing detector with a mechanical shutter operated by a wheel.
U.S. Pat. No. 3,253,140 to Sibley et al. discloses a system with an angled detector for recording the temperature of a wheel hub, wheel web and wheel rim.